Fluid sensing arrangement and mixing system

ABSTRACT

A sensing arrangement for sensing one or more properties of a fluid is provided. The sensing arrangement includes a fluid flow path ( 3 ) and a sensing means ( 5 ) to sense one or more properties of the fluid. The sensing means ( 5 ) is positioned or positionable within the fluid flow path ( 3 ). In use, the sensing arrangement directs the fluid in a substantially spiral flow ( 2 ) within the fluid flow path ( 3 ) past the sensing means ( 5 ). Also provided is a method of sensing one or more properties of a fluid and a fluid system for controlling one or more properties of a fluid.

TECHNICAL FIELD

The present invention relates to improvements in and relating to fluidproperty sensing arrangements and more particularly, but not exclusivelyto a mixing system including a temperature sensing arrangement of adesign that is able to contribute towards improved temperature sensingand/or a method of improved temperature sensing in a mixing valve.

BACKGROUND

To the present time, the accurate sensing of temperature of a fluidresulting from the mixing of fluids of different temperatures has proveddifficult and false temperature values can easily be obtained due to theincomplete mixing of the fluids and/or the positioning of thetemperature sensor. For valve systems and the like that rely on accuratetemperature sensing as a control signal, inaccuracies in temperaturemeasurement may be particularly problematic. Similar problems may resultwith mixing of any fluids having different properties, where thoseproperties need to be measured in the mixed fluid.

The term “fluid” is used throughout this specification to cover bothliquids and gases. However, by way of simplicity, the present inventionwill be described particularly in respect of its use in the temperaturesensing in conjunction with a mixing valve used for the mixing of hotand cold liquids.

In a domestic or industrial water supply, where hot and cold water isbeing mixed, a particular problem can be experienced where the hot andcold water pressures and variable hot and cold inlet orifices aresubstantially equal. This circumstance seems to promote a particulardifficulty in correctly ascertaining the temperature of the mixed water,which will ultimately be supplied to the end user.

OBJECTS OF THE INVENTION

The present invention, therefore, has as one object of one embodiment toprovide improved temperature sensing in or for a fluid mixing systemthat overcomes or alleviates problems in fluid mixing systems atpresent. Another or alternative object of the invention is to providethe public with a useful alternative.

Further objects of the invention, according to its various embodiments,will become apparent from the following description.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided asensing arrangement for sensing one or more properties of a fluid, thesensing arrangement including a fluid flow path and a sensing means tosense one or more fluid properties positioned or positionable within thefluid flow path, wherein in use, the sensing arrangement directs thefluid in a substantially spiral flow within the fluid flow path past thesensing means.

Preferably, the sensing arrangement may include an inlet through whichfluid enters the fluid flow path, wherein the fluid inlet is located offcentre and oriented to include a transverse component relative to thefluid flow path so as to create the spiral flow.

Preferably, the fluid inlet may be oriented substantially perpendicularto the fluid flow path.

Preferably, the sensing means may be positioned approximately 1.5 D awayfrom the fluid inlet, where D is the diameter of the fluid inlet.

In an alternative embodiment, the sensing means may be positioned lessthan 1.5 D away from the fluid inlet, when D is the diameter of thefluid inlet.

Preferably, the sensing means may be position d approximately 0.25 Ainto th fluid flow path where A is the diameter of the fluid flow path.

Preferably, the ratio of D:A may be approximately 0.65:1.

Preferably, the sensing means may sense the temperature of fluid withinthe fluid flow path.

Preferably, the sensing arrangement may be located downstream of a fluidmixing system fed from at least two fluid supplies, the fluid mixingsystem having an outlet that forms the inlet to the sensing arrangement.

Preferably, the fluid mixing system may be fed with a hot and a coldwater supply and wherein the sensing arrangement provides a signalindicative of the temperature of the fluid to a control means forcontrolling supply of hot and cold water from the hot and cold watersupply.

According to a further aspect of the present invention, a method ofsensing one or more properties of a fluid includes providing atemperature sensing means and providing in a fluid flow path a spiralflow of a fluid of which one or more properties is to be sensed, andpositioning the sensing means within said spiral flow.

Preferably, the method may include creating the spiral flow by directingfluid into the fluid flow path through an inlet located off centre andat an orientation including a transverse component to said fluid flowpath.

Preferably, the method may include directing fluid into the fluid flowpath substantially transverse to the fluid flow path.

Preferably, the method may include positioning the sensing meansapproximately 1.5 D away from the fluid inlet, where D is the diameterof the fluid inlet.

In an alternative embodiment, the method may include positioning thesensing means less than 1.5 D away from the fluid inlet, where D is thediameter of the fluid inlet.

Preferably, the method may include positioning the sensing meansapproximately 0.25 A into the fluid flow path, where A is the diameterof the fluid flow path.

Preferably, the ratio of D:A may be approximately 0.65:1.

According to another aspect of the present invention, there is provideda fluid system for controlling one or more properties of a fluid, thefluid system including a fluid flow path for the fluid and at least onesensor to sense one or more properties of the fluid and provide acontrol signal to a controller for controlling at least one of the oneor more properties of the fluid dependent on the control signal, whereinin use, the fluid system directs fluid through the fluid flow path in asubstantially spiral flow and the at least one sensor is located withinthe fluid flow path.

Preferably, the fluid within the fluid flow path may be downstream of alocation of mixing of at least two fluids.

Preferably, the fluid system may include an inlet to the fluid flowpath, wherein the fluid inlet is located off centre and oriented toinclude a transverse component relative to the fluid flow path so as tocreate the spiral flow.

Preferably, the at least one sensor may be positioned approximately 1.5D away from the fluid inlet, where D is the diameter of the fluid inlet.

In an alternative embodiment, the at least one sensor may be positionedless than 1.5 D away from the fluid inlet, where D is the diameter ofthe fluid inlet.

Preferably, the at least one sensor may be positioned approximately 0.25A into the fluid flow path where A is the diameter of the fluid flowpath.

Preferably, the ratio of D:A may be approximately 0.65:1.

Preferably, the at least one sensor may sense the temperature of fluidwithin the fluid flow path.

Preferably, the fluid system may be used to sense one or properties ofwater, wherein the controller controls the supply of at least twosupplies of water, each supply at a different temperature.

According to a further aspect of the present invention, there isprovided a sensing arrangement for a fluid substantially as hereindescribed and with reference to the accompanying drawings.

According to still further aspect of the present invention, there isprovided a method of sensing one or more properties of a fluidsubstantially as herein described and with reference to the accompanyingdrawings.

According to another aspect of the present invention, there is provideda fluid system for controlling one or more properties of a fluidsubstantially as herein described and with reference to the accompanyingdrawings.

Further aspects of this invention, which should be considered in all itsnovel aspects will become apparent from the following description, givenby way of example of a possible embodiment thereof and in whichreference is made to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: shows diagrammatically a temperature sensing arrangementaccording to one possible embodiment of the invention;

FIG. 2: shows very diagrammatically a plan view of the temperaturesensing arrangement of FIG. 1;

FIG. 3: shows very diagrammatically an end view of the temperaturesensing arrangement of the preceding figures; and

FIG. 4: shows a plan view of one possible embodiment of a mixing valveto which the present invention may relate.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention includes a sensing arrangement for a fluid, whichmay be used as part of a control system for fluid mixing. The sensingarrangement includes a fluid flow path, in which fluid is directed in asubstantially spiral flow within the fluid flow path is located a sensorto detect a property of the fluid.

The invention may have application to industrial and domestic watersupply temperature measurement. The spiral flow induced in the fluid mayallow the temperature sensor to be located close to the location offluid mixing and close to the feed of water to be mixed. Therefore,where the temperature measurement forms part of a control system afaster response time may result.

However, the present invention may have application to fluids other thanwater and to the detection of properties of a fluid other thantemperature. The fluid may be liquid, gas, a vapour or in a mixture ofstates. Sensing arrangements in accordance with the invention may senseone or a number of properties of the fluid and may be used in thecontrol of one, all or any combination of properties.

Thus, although the following description has been give with particularreference to the sensing of temperature of a liquid and particularly thetemperature of mixed hot and cold water, the invention is not limited tosuch an implementation. It will be appreciated that the presentinvention could be used in detecting one or more specifiedproperties/characteristics of any required fluid or mixture of fluids,for example pH, viscosity, colour and/or composition.

Referring particularly to FIG. 1, a fluid the temperature of which isrequired to be sensed, is shown flowing in a direction A into an inlet 1from which it will flow along a conduit or passage way 3. The flow offluid is indicated very diagrammatically by the spiral 2 with the flowof fluid into the passageway 3 being offset relative to a central axisof the inlet 1 so that as the fluid enters substantially tangentiallyinto the passageway 3, the fluid will commence a spiral flow asindicated in a direction indicated by arrow B. A bulbous chamber 4 maybe provided at the entrance to assist in the formation of the spiralflow. It is envisaged that suitable means such as some baffling may beprovided to enhance the spiral inducing effect as will be apparent tothose skilled in the art.

By providing an offset tangential entry of the fluid along the arrow A,a spiral flow is created essentially by the curvature of the inner wallsof the passageway 3. The inlet 1 may not necessarily feed fluid into thepassageway 3 perpendicular to the direction of travel of the fluid alongthe passageway, although this is the preferred embodiment. By changingthe angle of feed of the fluid to the passageway 3 to include acomponent along the passageway 3, the number of revolutions in thespiral flow per unit distance along the passageway may be varied. Also,the speed of the fluid along the passageway 3 may be affected.

A temperature sensing means 5 is shown positioned relative to the inlet1. The sensing means 5 is shown with a probe 6 directed into the spiralflow 2. Suitable sensors for temperature measurement includethermocouples or a thermistors. Where properties of the fluid other thantemperature are being sensed, a suitable sensor to detect that or thoseproperties is provided.

As indicated in FIG. 2, the positioning of the temperature sensing means5 relative to the inlet 1 may be at approximately 1.5 D where “D” is thediameter of the inlet 1 or may be closer, for example 1.0 D. A benefitof the present invention is that the sensing means 5 may be positionedin this way relatively close to the inlet 1 so that the unit is compact.This may improve the response time of any control system dependent onthe sensed property or properties. It will be appreciated, however, thatif compactness was not an issue, then the sensing means 5 could bepositioned wherever appropriate along the length of the passageway 3.The performance of the sensing arrangement may vary depending on thepositioning of the sensing means 5 and the position for optimalperformance may vary depending on the fluids used, their speed throughthe fluid flow path and the shape of the spiral flow within the fluidflow path.

Referring now to FIG. 3, the probe 6 may extend for exampleapproximately 0.25 A into the passageway 3 where “A” is the diameter ofthe passageway 3, although this distance is determined by the mostappropriate position according to the flow characteristics in thepassageway 3. The probe 6 may permanently extend into the passageway 3,or may be removable or retractable if required, wherein the probe isextended into the passageway 3 to obtain sample measurements.

An added benefit of the invention is that mixing may be achieved withoutthe use of baffles or the like which would interfere with the fluidflow.

Referring particularly to FIG. 3, the positioning of the inlet 1relative to the passageway 3 is shown as providing an essentiallytangential entry of the fluid into the passageway 3 to create the spiraleffect. The inlet 1 may receive fluid from a mixing system to whichwater of two different temperatures is supplied. The mixing system maybe of any suitable type, which may depend on the fluid to be sensed.

Although the invention may be used to measure properties of a fluidpassing through a passageway wherein the inlet fluid is the same as theoutlet fluid, the invention is anticipated to have particularapplication to when some properties of the fluid have changed. A commonexample of this is the mixing of two fluids into one. However, otherchanges may be implemented such as heating using an external source,introduction of an additive to the fluid flow or any other change thatmay be required as part of a fluid cycle or process. The presentinvention may be used to control such changes.

Referring to FIG. 4, the temperature sensor 5 is shown provided as partof a mixing valve 10 with a typical control mechanism 9 controlling themixing of hot and cold fluids flowing into the mixing valve 10 throughinlets 7 and 8 respectively and leaving through the passageway 3. Themixing valve 10 combines the fluids from inlets 7 and 8 into a singlefluid flow to the inlet 1. The mixing valve 10 may include a mixingchamber or the like to encourage mixing of the two fluids. Turbulencemay be introduced to the flow within the mixing chamber to assist mixingif required.

The control mechanism 9 may be operated by a stepper motor, which inturn is controlled by a suitable control circuit (not shown). Thecontrol circuit may receive as an input a signal from the temperaturesensor 5. The control circuit may control the stepper motor toprogressively open or close the inlets 7 and 8 dependent on whether thesignal from the temperature sensor 5 indicates a temperature above orbelow a predetermined set point. Those skilled in the relevant arts willrecognise that there are a large number of possible control apparatusand control methodologies that may be used.

The ratio of the diameters of the inlet 1 and the passageway 3 may beadjusted to optimise the spiral action mixing of the fluid in thepassageway 3. If appropriate, an insert may be provided in the inlet 1and/or the passage 3 to provide the optimal ratio. It has been foundthat a small diameter D of inlet 1 relative to diameter A of passageway3 may provide an optimal result. A ratio of D:A of approximately 0.65:1is one which has provided good test results for good temperature sensingand flow.

The mixing valve 10 may be constructed from moulded metal to form therequired fluid passageways. Seals are provided at joints where requiredto avoid leaks. The materials used, dimensions of the mixing valve 10and dimensions of the passageways may vary depending the fluid/s usedand the required rate of fluid communication through the mixing valve.

Where in the foregoing description, reference has been made to specificcomponents or integers of the invention having known equivalents thensuch equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and withreference to possible embodiments thereof, it is to be understood thatmodifications or improvements may be made thereto without departing fromthe scope of the invention as defined in the appended claims.

1. A sensing arrangement for sensing one or more properties of a fluid,received from a mixing system, the sensing arrangement including a fluidflow path and a sensor to sense one or more fluid properties positionedor positionable within the fluid flow path, and a fluid inlet throughwhich fluid enters the fluid flow path, wherein the fluid inlet islocated and oriented to include a transverse component relative to thefluid flow path so as to create a substantially spiral flow within thefluid flow path past the sensor.
 2. The sensing arrangement of claim 1,the fluid inlet through which fluid enters the fluid flow path ispositioned off-center relative to the fluid flow path.
 3. The sensingarrangement of claim 1, wherein the fluid inlet is orientedsubstantially perpendicular to the fluid flow path.
 4. The sensingarrangement of claim 3, wherein the sensor is positioned within adistance of approximately 1.5 D from the fluid inlet, where D is thediameter of the fluid inlet.
 5. The sensing arrangement of claim 4,where A is the diameter of the fluid flow path and wherein the ratio ofD:A is approximately 0.65:1.
 6. The sensing arrangement of claim 5,wherein the sensor is positioned approximately 0.25 A into the fluidflow path.
 7. The sensing arrangement of claim 4, wherein the sensor ispositioned approximately 0.25 A into the fluid flow path, where A is thediameter of the fluid flow path.
 8. The sensing arrangement of claim 1,wherein the sensor is positioned approximately 1.5 D away from the fluidinlet, where D is the diameter of the fluid inlet.
 9. The sensingarrangement of claim 1, wherein the sensor is positioned less than 1.5 Daway from the fluid inlet, where D is the diameter of the fluid inlet.10. The sensing arrangement of claim 1, wherein the sensor is positionedapproximately 0.25 A into the fluid flow path, where A is the diameterof the fluid flow path.
 11. The sensing arrangement of claim 10, whereinthe sensor is positioned within approximately 1.5 D from a fluid inletthrough which fluid enters the fluid flow path, where D is the diameterof the fluid inlet and wherein the ratio of D:A is approximately 0.65:1.12. The sensing arrangement of claim 1, wherein the sensor senses thetemperature of fluid within the fluid flow path.
 13. The sensingarrangement of claim 1, wherein the sensing arrangement is locateddownstream of a fluid mixing system fed from at least two fluidsupplies, the fluid mixing system having an outlet that forms the inletto the sensing arrangement.
 14. The sensing arrangement of claim 9,wherein the fluid mixing system is fed with a hot and a cold watersupply and wherein the sensing arrangement provides a signal indicativeof the temperature of the fluid to a control means for controllingsupply of hot and cold water from the hot and cold water supply.
 15. Thesensing arrangement of claim 1, wherein the diameter of the fluid inletis approximately 65% of the diameter of the fluid flow path.
 16. Thesensing arrangement of claim 15, wherein the sensor is positioned withina distance of approximately 1.5 D from the fluid inlet, where D is thediameter of the fluid inlet.
 17. The sensing arrangement of claim 1wherein the sensing arrangement directs fluid in a substantially spiralflow within the fluid flow path substantially without the use ofbaffles.
 18. A method of sensing one or more properties of a fluidincluding receiving the fluid of which one or more properties is to besensed from a mixing system, providing a fluid flow path for the fluid,providing a sensor and providing in the fluid flow path a spiral flow bydirecting the fluid into the fluid flow path through an inlet locatedand oriented to have a transverse component to the fluid flow path, andpositioning the sensor within said spiral flow.
 19. The method of claim18, including creating the spiral flow by directing fluid into the fluidflow path through an inlet located and oriented off-center relative tosaid fluid flow path.
 20. The method of claim 18, including directingfluid into the fluid flow path substantially transverse to the fluidflow path.
 21. The method of claim 20, including positioning the sensorwithin a distance of approximately 1.5 D from the fluid inlet, where Dis the diameter of the fluid inlet.
 22. The method of claim 21, where Ais the diameter of the fluid flow path and wherein the ratio of D:A isapproximately 0.65:1.
 23. The method of claim 21, including positioningthe sensor approximately 0.25 A into the fluid flow path.
 24. The methodof claim 21, including positioning the sensor approximately 0.25 A intothe fluid flow path, where A is the diameter of the fluid flow path. 25.The method of claim 18, including positioning the sensor approximately1.5 D away from the fluid inlet, where D is the diameter of the fluidinlet.
 26. The method of claim 18, including positioning the sensor lessthan 1.5 D away from the fluid inlet, where D is the diameter of thefluid inlet.
 27. The method of claim 18, including positioning thesensor approximately 0.25 A into the fluid flow path, where A is thediameter of the fluid flow path.
 28. The method of claim 27, includingpositioning the sensor approximately 1.5 D away from the fluid inlet,where D is the diameter of the fluid inlet and wherein the ratio of D:Ais approximately 0.65:1.
 29. The method of claim 18, wherein thediameter of the fluid inlet is approximately 65% of the diameter of thefluid flow path.
 30. The method of claim 29, wherein the sensor ispositioned within a distance of approximately 1.5 D from the fluidinlet, where D is the diameter of the fluid inlet.
 31. The method ofclaim 18 wherein providing in the fluid flow path a spiral flow includesproviding a spiral flow substantially without the use of baffles.
 32. Afluid system for controlling at least one property of a fluid, the fluidsystem including a fluid flow path for the fluid and at least one sensorto sense at least one property of the fluid and provide a control signalto a controller for controlling at least one of the properties of thefluid sensed by the at least one sensor dependent on the control signal,and a fluid inlet through which fluid enters the fluid flow path,wherein the fluid inlet is located and oriented to include a transversecomponent relative to the fluid flow path so as to create asubstantially spiral flow within the fluid flow path past the sensor.33. The fluid system of claim 32 wherein the fluid inlet is located andoriented to be off-center relative to the fluid flow path so as tocreate the spiral flow.
 34. The fluid system of claim 32, wherein thefluid flow path is downstream of a location of mixing of at least twofluids.
 35. The fluid system of claim 34, wherein the at least onesensor is positioned approximately 1.5 D away from the fluid inlet,where D is the diameter of the fluid inlet.
 36. The fluid system ofclaim 34, wherein the at least one sensor is positioned less than 1.5 Daway from the fluid inlet, where D is the diameter of the fluid inlet.37. The fluid system of claim 34, wherein the fluid inlet is orientedsubstantially perpendicular to the fluid flow path.
 38. The fluid systemof claim 32, wherein the at least one sensor is positioned approximately0.25 A into the fluid flow path, where A is the diameter of the fluidflow path.
 39. The fluid system of claim 38, wherein the sensor ispositioned within approximately 1.5 D from a fluid inlet to the fluidflow path, where D is the diameter of the fluid inlet and wherein theratio of D:A is approximately 0.65:1.
 40. The fluid system of claim 39,wherein the fluid inlet is oriented transverse to the fluid flow pathand off-center of the fluid flow path so as to create said spiral flow.41. The fluid system of claim 32, wherein the at least one sensor sensesthe temperature of fluid within the fluid flow path and wherein fluidsof different temperatures are mixed under the control of the controllerat said location of mixing of at least two fluids.
 42. The fluid systemof claim 32 when used to sense one or more properties of water andwherein the controller controls the supply of at least two supplies ofwater to said location of mixing, each supply at a differenttemperature.
 43. The fluid system of claim 32, wherein the fluid inletis oriented substantially perpendicular to the fluid flow path and theat least one sensor is positioned within 1.5 D from the fluid inlet,where D is the diameter of the fluid inlet.
 44. The fluid system ofclaim 43, wherein the diameter of the fluid inlet is approximately 65%of the fluid flow path.
 45. The fluid system of claim 43, wherein the atleast one sensor is positioned approximately 0.25 A into the fluid flowpath, where A is the diameter of the fluid flow path.
 46. The fluidsystem of claim 32, wherein the diameter of the fluid inlet isapproximately 65% of the diameter of the fluid flow path.
 47. The fluidsystem of claim 46, wherein the at least one sensor is positioned within1.5 D from the fluid inlet, where D is the diameter of the fluid inlet.48. The fluid system of claim 43 wherein the fluid inlet is located andoriented to create a substantially spiral flow within the fluid flowpath past the sensor substantially without the use of baffles.
 49. Asensing arrangement for sensing one or more properties of a fluid, thesensing arrangement including a fluid flow path extending in a firstdirection, a sensor position in the fluid flow path to allow a sensor tosense one or more fluid properties when positioned within the fluid flowpath, and a fluid inlet downstream from a fluid mixing area and upstreamfrom the sensor position, the fluid entering the fluid flow path fromthe fluid inlet, wherein the fluid inlet is oriented at least partlytransverse to the first direction and located relative to the fluid flowpath so as to create a substantially spiral flow within the fluid flowpath past the sensor.
 50. The sensing arrangement of claim 49 whereinthe fluid flow path has a curvature and wherein the fluid inlet isoriented substantially on a tangent to the curvature of the fluid flowpath.
 51. The sensing arrangement of claim 50 wherein the fluid inlet iscentered substantially off center of the flow path.
 52. The sensingarrangement of claim 49 further including a mixing chamber upstream fromthe fluid inlet, wherein the fluid inlet is between the mixing chamberand the temperature sensor, and the inlet and the flow passage areconfigured so that the substantially spiral flow occurs between thefluid inlet and the sensor.